Q. Some friends of mine who are lawyers were recently discussing a political corruption prosecution that they seemed to think was a big deal. I believe it involved some sort of campaign finance violations by the campaign manager of someone who ran for Congress a few years back. As a non-lawyer, it wasn’t clear to me what all the fuss was about. After all, people get prosecuted for political corruption all of the time. Are you aware of the case I’m describing, and, if so, what makes it such a big deal? A. I believe I am. Last month, the Department of Justice announced a political operative named Tyler Harber pleaded guilty to crimes stemming from campaign finance improprieties in the 2012 federal election. The DOJ’s press release said, “This is the first criminal prosecution in the United States based upon the coordination of campaign contributions between political committees.”

OK, fine, but what does that mean?

To understand, it helps to review some background on campaign finance law and the types of committees that raise money for political spending. Candidates in congressional elections typically establish candidate committees to raise funds for their campaigns. The law imposes strict limits on the amount of money a candidate’s committee may receive from a given individual. Currently, for each election an individual may not contribute more than $2,600 to a candidate committee.

Corporations may not contribute at all. The idea is to prevent any single donor from currying undue influence over members of Congress by contributing large amounts of money to help them get elected.

While the Supreme Court allows these limits on contributions to candidate committees, it has struck down other limitations on political spending as violations of the First Amendment’s right to free speech. Notably, the law imposes no limits at all on an individual’s own expenditure of money to advocate the election of a particular candidate, so long as the expenditure is made independently of the candidate and the candidate’s committee. These are known as “independent expenditures.” While there is no limit on how much anyone may spend on an independent expenditure, individuals who make such expenditures must report them and disclose the sources of funds used for the expenditure.

The law also allows the formation of independent-expenditure-only political action committees, which are known as super PACs. There are no limits on the amounts of money super PACs may spend on advocating the election of a candidate or the amounts they may accept from any particular donor. The key, again, is they must not coordinate with a candidate or a candidate’s committee.

As you can see, a lot turns on what counts as “coordination.” According to federal law, a communication is coordinated if it is “made in cooperation, consultation or concert with, or at the request or suggestion of, a candidate, a candidate’s authorized committee or their agents, or a political party committee or its agents.”

Which brings us to the Harber case. In 2012, Harber was the campaign manager for Republican Chris Perkins, who unsuccessfully challenged incumbent Virginia Democratic Rep. Gerald E. Connolly for his congressional seat. According to court documents, during the campaign Harber started a super PAC which, records show, was called National Republican Victory Fund. While serving as campaign manager for Perkins, Harber “made and caused” $325,000 in coordinated expenditure contributions from the super PAC to Perkins’ campaign committee.

After a wealthy donor made the maximum legal contribution to Perkins’ campaign committee, Harber directed the donor to contribute to the National Republican Victory Fund. The donor contributed $300,000, and Harber bought $325,000 in ads opposing Connolly’s re-election. Harber then took steps to cover up his involvement including lying about it to the FBI when the bureau interviewed him while investigating the matter in 2013.

He pleaded guilty to two offenses: making illegal coordinated contributions and making false statements to the government. His sentencing is scheduled for June, and for each offense, he faces up to five years in prison and fines up to $250,000. By pleading guilty and agreeing to cooperate with the government, Harber may of course receive a reduced penalty. But, his case is nevertheless a reminder that coordination is illegal. This may have been the first prosecution for coordination between campaign committees. But, it will not be the last.